The presence of repeated runout (RRO) error can adversely affect the ability of a control system to correctly position a control object. RRO error generally comprises repetitive error in an observed state, such as “once-around” errors that are exhibited during each revolution in a rotating system.
Some data storage devices utilize servo data written to one or more rotatable storage media to provide servo positioning information. This information provides feedback to a closed loop servo circuit that operates to position a transducer adjacent tracks on the media. Misalignments of the servo data can produce RRO error in the observed actual position of the transducer, thereby reducing servo control margins.
Error compensation techniques, such as the application of zero acceleration path (ZAP) processing, can be applied in an effort to reduce the effects of such misalignments. Such processing, however, can be time and computationally intensive.